Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int main(){
  int H,W;
  cin>>H>>W;
  vector<string> data(H);
  for(int i=0;i<H;i++){
    cin>>data[i];
  }
  vector<vector<int>> dist(H,vector<int>(W,-1));
  using pir=pair<int,int>;
  queue<pir> que;
  dist[0][0]=0;
  que.push(pir(0,0));
  int dx[4]={0,0,1,-1};
  int dy[4]={1,-1,0,0};

  while(!que.empty()){
    auto v=que.front();
    que.pop();
    for(int i=0;i<4;i++){
      int nx=v.second+dx[i];
      int ny=v.first+dy[i];
      if(nx<0||nx>=W||ny<0||ny>=H)continue;
      if(data[ny][nx]=='#')continue;
      if(dist[ny][nx]!=-1)continue;
      dist[ny][nx]=dist[v.first][v.second]+1;
      que.push(pir(ny,nx));
    }
  }
  int all=H*W;
  int tmp=0;
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      if(data[i][j]=='#') tmp++;
    }
  }
  if(dist[H-1][W-1]==-1)cout<<-1<<endl;
  else{
    int ans=all-tmp-dist[H-1][W-1];
    cout<<ans-1<<endl;
  }
}